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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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The RAIN scale: A good intention that falls short
Radiation protection specialists agree that clear communication of radiation risks remains a vexing challenge that cannot be solved solely by finding new ways to convey technical information.
Earlier this year, an article in Nuclear News described a new radiation risk communication tool, known as the Radiation Index, or, RAIN (“Let it RAIN: A new approach to radiation communication,” NN, Jan. 2025, p. 36). The authors of the article created the RAIN scale to improve radiation risk communication to the general public who are not well-versed in important aspects of radiation exposures, including radiation dose quantities, units, and values; associated health consequences; and the benefits derived from radiation exposures.
Yousef M. Farawila
Nuclear Science and Engineering | Volume 129 | Number 3 | July 1998 | Pages 261-272
Technical Paper | doi.org/10.13182/NSE98-A1980
Articles are hosted by Taylor and Francis Online.
A modal neutron kinetics method was developed and applied to new problems with boiling water reactor oscillations. The modal method is uniquely suited for such problems because the oscillation components, in-phase and out-of-phase, correspond directly to separate expansion functions. One problem is understanding the origin and predicting the magnitude of the in-phase component that is always present during out-of-phase power oscillations. Another exercise of the method was the calculation of the relative critical power ratio (CPR) response to in-phase and out-of-phase oscillations, known as the DIVOM curve, using a fast single hydraulic channel model. The new calculations confirm the BWR owners group results and similar calculations using the full three-dimensional neutronics and multichannel models of the RAMONA-3 code. In addition, the origin of the large difference between the in-phase and out-of-phase CPR responses could be explained. Modal analysis of the reactivity biases associated with oscillating reactivity insertions for the two known modes could explain the out-of-phase mode higher propensity to growth compared with the in-phase mode of oscillation.